Air Hog

[bjexpat]

Compared to guys I dive with, I'm a bit on an the large stature side of things...over 6'2" and carrying some mass around 220 lbs. It's really frustrating that I'm running out of air before everyone else I dive with by a 50%. Also, I'm finding that my self-consciousness about air consumption is making me more anxious and thus less efficient.

So besides following a number of breathing tips/tricks and aerobic conditioning, what are the considerations for using twins or oversized tanks? The weight on land doesn't scare me because I can lift quite a bit but I have some questions?

Do twins require special certs/training? Can recreational back inflate BCs carry twins? Or would I need to look at backplates w/wings?

 

[DivingPrincessE]

I think you should consider just buying larger steel tanks (120s, 130s) before messing around with doubles. You seem to be pretty early on in your diving career to be thinking about going to doubles. 120s and 130s should give you more than enough air, especially if you're diving with people using AL80s.

(Yes I am also a newish diver, so maybe shouldn't be giving "dive advice". However, I am basing this on the more experienced people I dive with and the tanks they use.)

 

[boulderjohn]

I don't know what kind of diving you do in China, but if you are doing any kind of resort diving requiring travel, using doubles will not be helpful, since you won't be bringing them with you and will be instead using what everyone else is using.

Either way, it is better to work on your own air consumption first. With your size, you will never breathe like a 130 pound woman, but there is much you can do to improve. If you are breathing in a calm, relaxed manner, than you are doing about all you can with that. "Breathing tricks" are generally not helpful, and some are harmful.

The most likely cause of your breathing difficulties, at least based on what I see with most beginning divers, is in swimming technique. Do you have a nice, streamlined horizontal trim when you swim, or are your feet well below your shoulders? Do you have good buoyancy so that if you were to stop all movement you would essentially hang in place, or are you constantly kicking, however gently, to maintain your depth? Do you swim with a gentle body, your arms calmly folded across your chest, or do your hands wave to help you with direction and depth? Do you swim gently and almost lazily, or are you working hard or darting about? Inefficient body movement is a prime cause of excessive air consumption.

Back to your original question: Some BCD's can be adapted to doubles, and there is some moderate traiing required for simple double usage. If you are only looking to keep up with your dive companions and their single tanks, an easier solution would be to get a bigger tank. There are single tanks you can strap on your present gear that will more than make uo for the difference you are talking about.

 

[ligersandtions]

According to your profile, you have 0-24 dives....I'm going to go ahead and assume this is correct. Based on the number of dives you have, I would guess that you haven't gotten your buoyancy nailed down yet. You're probably either fighting to get or stay neutral....or you are negatively buoyant and are swimming to keep yourself from sinking. Whatever the issue is, if you are struggling to be neutral (or just aren't neutral and don't know it), you're going to suck through a lot more air than a more experienced diver. Take some time and figure out your buoyancy....drop down, hover, just hang out, don't kick, don't move....feel what it's like to be neutral, and then strive for that when you're actually moving around the reef.

When you've figured out your buoyancy, you'll need to focus on a couple more things: trim and weighting. You want to trim out horizontally because that will give you the most streamlined profile you can have, and that leads to the least resistance when you're swimming. The less the resistance, the less effort you have to put forth....the less effort you put forth, the less air you will consume. Finally, you want to be weighted properly so you don't have to compensate for unnecessary weight. Make sure you can hold a safety stop at the end of your dive (wing empty, tank with less than 500 psi, 10-15 feet of water). Whatever weighting allows you to do so is your proper weighting....don't add more, don't dive with less.

Finally, after you gain some experience, figure out your buoyancy, trim, and weighting....if you still suck through your air at a much higher rate than your buddies, consider a bigger tank. A steel 100 or 130 is a good start. I would recommend staying away from doubles until you are more experienced, but a large steel tank is a wonderful investment.

 

[speedhound]

I agree with the guys above, and have a couple of thoughts to share.
Your profile says you're early in your diving career, probably still having to work at things, and almost certainly a bit anxious about diving and air consumption.

As you relax with experience and practice, and you will, your breathing rate will come down naturally.
From my own experience if you do some/more exercise and get fitter on land, that too will improve your breathing rate over time.

In the meantime, enjoy your diving. See if there's anyone nearby that may uses more air than most. I'm sure they'd be happy to find a buddy with the same requirements as themselves, and to improve together with. Hey, you'd be able to fit in three dives while others could only do two!

Diving isn't about staying down for the longest time, it's about enjoying yourself while you're doing it. Go out, dive safe, and have fun!

 

[TSandM]

To some extent, your gas consumption IS affected by how big a person you are. The determinant of how much gas has to go in and out of the lungs in a given period of time is CO2 production by the tissues, and somebody with more muscle mass is going to make more CO2 than somebody smaller. But with that said, one of my favorite dive buddies is a man about 5'10" and 250 pounds, and he almost perfectly matches me for SAC rate, and I'm half his size. How does he do it?

Well, first off, he's got a lot of experience, so he's very relaxed in the water. He also has very good buoyancy control, so he isn't adding and subtracting gas from his BC or his drysuit constantly during a dive. He swims SLOWLY, knowing that many of the things that live in the water are camouflaged, and a slow dive is more productive in terms of finding cryptic critters. He also maintains a horizontal position in the water, so all the energy he generates with his fins drives him forward.

A common issue for new divers is not only overweighting, but maldistribution of weights. If you are carrying a ton of weight around your waist, it will tend to drop your lower body. Your feet are then below your torso, and you are pointing upward. When you kick, you are driven UP. To avoid ascending, you have to keep your buoyancy negative, so your tendency to sink counteracts that drive to rise. There's a lot of wasted energy here! Often, moving some weight up onto the cambands or the neck of the tank will help you be able to maintain a horizontal position, and dive with neutral buoyancy and much greater efficiency.

Finally, it's worth playing with your weights and your body position to balance yourself in the water, so that you don't have to move ANYTHING unless you want to. If you can just sit in the water and look at whatever interests you, you are using almost no energy during that time, and your gas consumption will be minimal.

So, before you invest a lot of money in huge tanks (and I would NOT recommend doubles), spend some time in the water working on your technique. You may not need those big tanks after all!

 

[Anti-Hero]

By order of importance (IMO): Comfort, buoyancy, trim, physical size.

 

[RonFrank]

Larger tanks can be a big advantage to a larger diver. My buddy dives Al100's, and he is 6'5", maybe 250+ lbs. He has been diving for over 5 years, and his SAC rate will never be as low as many experienced divers.

You could purchase larger tanks, and work on your SAC rate. Over time it should improve, but there is no quick fix for this. I would look into larger singles. Doubles are more difficult to manage, and you would have to not only purchase a BP/W setup and doubes, but a new first stage as well. You would be looking at over 1K in equipment expenses easily, maybe more in the $1500 range.

Before doing that, I would either rent, or purchase a larger single tank. That would not require a new BC or regs, just a different tank. Some popular options range from an AL100 (larger 8" diameter) to Steel HP 95's, 100's, 120's, or 130's. Steel tanks are expensive. I would suggest renting for a while before jumping into that purchase.

TSandM's buoyancy comments are worth reviewing. Being more comfortable UW will improve air efficiency, but that does not happen overnight.

 

[LeadTurn_SD]

Just chiming in as another "large fellow" (I'm 6'5", 260 lbs).

Your air consumption will improve over time. Mine will never be as low as my wife's, who is 1/2 my weight and muscle mass.... but you can get it down to an "acceptable" rate (my RMV hovers around .7 for an "average" slow-swimming reef dive).

As others have already stated above, anything that you can do to increase your comfort level and decrease your physical exertion underwater will drop your air consumption rate.

Then just relax and enjoy diving. In the end, your body "needs what it needs", don't try to over-control your breathing as this just makes things worse.

Good Luck and Best Wishes.

 

[MMM]

One thing not mentioned besides practice/experience would be to ask yourself if you are cold when diving. If you are, then a warmer wetsuit could help.